Currently, there is a practical demand and necessity for research on how English-as-a-second language (ESL) learners acquire literacy skills, such as spelling. One important issue of this research agenda is how ESL learners apply first-language knowledge to learning to spell in English. Twenty-seven studies were reviewed that investigated the influence of the first language on ESL learners' development of English spelling skill. Evidence was found for both positive and negative transfer of first-language knowledge and processes to ESL learners' English spelling. These results are in agreement with theoretical propositions about the interdependence between first- and second-language academic skills [e.g., Cummins, J. (1981). In California State Department of Education (Ed.), "Schooling and language minority students: A theoretical framework" (pp. 3-49). Los Angeles: Evaluation, Dissemination, and Assessment Center, California State University, Los Angeles]. The findings are discussed in relation to the ESL learner's first-language proficiency level and distance between first language and English. Comparisons are drawn between ESL learners' and English monolinguals' spelling development and suggestions for future research are provided.